I last had guidance in playing my flute in 6th grade band class and I've been solo since. (About 7 years ago) So naturally everything I know, I gleaned off the internet. My notes are starting to sound better but there is something I'm just not sure how to fix. When changing notes, I tap my tongue to the top of my teeth to provide separation but it sounds kind of choppy. Even when I play fast and there's not much room for choppiness. I want it to sound smooth without blending the notes. Does anyone have any advice?
Starting a note with the tongue on or behind your teeth is called 'tonguing'. You can use a 'ta' syllable with the tongue touching your teeth or a 'da' syllable with the the tongue touching the roof of your mouth which gives a softer sound.
If you want to move between notes smoothly, don't tongue the second and subsequent notes and keep the air-stream moving.
I think going from a 'Te' syllable to a softer 'Du' will help.
The trouble I had when using 'Du' is that I used 'Te' as a sort of whip to create fast air to make it easier to get the second octave to sound, instead of using a good breath support. So maybe it's also a good idea when you're trying to play more smooth and tenuto to take care of your breath support. A way to practice this is playing without any tonguing at all, just using your belly. When you can do this you can add just a little bit of tongue to make the articulation.
It will also help to think of the line you're playing as one large legato line (again breath support!) that's only briefly interrupted with little tongue pulses. To accomplish this you can also practice it legato without tonguing, in one large breath, and really take care of your phrasing. When you can do that you can add tonguing.